Within the paperboard tube industry, it is desirable to minimize the amount of ply material used to manufacture a paperboard tube. Paperboard tube structures are often used in consumer good applications such as paper towel rolls or toilet paper rolls, but they are also used in manufacturing applications such as cores for supporting rolled sheet material or in industrial applications such as forms or templates for columnar structures.
Tube structures must possess structural properties commensurate with their intended applications. Paperboard tube designs and manufacturing procedures preferably should minimize the amount of raw materials needed to achieve the required structural properties for the particular tube structure. By reducing the material needed, the expense of producing the paperboard tube structures will likewise decrease.
The bending stiffness and other strength properties of tube structures depend on a number of factors, including the strength of the individual plies of the tube and the wall thickness of the tube. As a general rule, increasing the wall thickness of a tubular structure will result in a stronger tube. An increase in wall thickness can be brought about by using additional plies and/or using thicker plies. In either case, an additional amount of raw material is required, which increases the cost of the paperboard tube. Tube strength can also be increased by using denser, stronger plies, but such stronger plies are relatively more costly.
Therefore, a need exists for a paperboard tube structure requiring a minimal amount of paperboard material while maintaining adequate tube strength.